Medical catheters for insertion into the human body are well known. It is also well known that such catheters have to be constructed such that the distal end of the catheter follows the movement of the proximal end. The manipulation of the distal end in response to the movement of the proximal end is important in order to be able to negotiate the catheter into bends and openings encountered along the insertion path.
The difficulties in providing a structure for the catheter which permits remote manipulation of the distal end are particularly intractable in long catheters as are required of angioplast guiding and diagnostic catheters which thread from the thigh to the heart. Such catheters are fifty to sixty inches long and have outside diameters of 8 to 9 French (a French=3.3 mils). Remote control of the distal end of such a catheter is difficult to achieve and therefore very expensive.
At the present time there are three approaches to making catheters which exhibit sufficient structural integrity to provide the torque necessary to manipulate the distal end as required. The first include a plastic tube encased in a wire mesh which in turn is encased in a plastic biocompatible tube. It is clear that catheter structures of this type require three separate operations to fabricate.
There are alternate techniques for making such catheters. One substitutes a nylon braid for the wire braid. Another substitutes a fiberglass-epoxy layer for the braid. It is clear that still three separate fabrication operations are needed. Commercially available diagnostic catheters of this type have at least a nine French outside diameter.